In circuit breakers, the two coaxially opposite auxiliary contacts, frequently referred to as arcing contacts, are coaxially surrounded by two permanent-current contacts, one of which is stationary and the other designed to move in an axial direction. Circuit breakers of this type usually work with a gaseous quenching agent that flows through the area separating the contacts during switching and whose flow can be influenced by special compression chambers and nozzles. Among other things, an insulating nozzle that is located within the permanent-current contacts, surrounds the arcing contacts, and can be permanently connected to both the drivable permanent-current contact and the driven arcing contact, is used for this purpose.
In a conventional circuit breaker of this type, as described in, for example, European Patent No. 0 313 813, a driving element is attached to the insulating nozzle, which transmits the driving movement of the driven permanent-current contact to the second arcing contact via corner gears in such a way that the two arcing contacts are driven in opposite directions. For this purpose, the second arcing contact is inserted into a sliding contact. In the known corner gears, the driving element is designed as a gear rack that acts upon the second arcing contact, which is also designed as a gear rack, via a gear wheel. The driving movement of the insulating nozzle is transmitted linearly onto the second arcing contact being driven in the opposite direction. Alternatively, the corner gears can also be a locking mechanism having a ratchet gear that is moved by the driven contacts and a clamping part equipped with a compression spring, with the clamping part driving the arcing contact moving in the opposite direction in a pulsating manner after a ratchet clears the ratchet gear.
In another conventional circuit breaker of this type, a crank can also be used as the corner gear, with its rotating part being formed by the gear wheel that is driven by the gear rack connected to the insulating nozzle, as described in, for example, European Patent No. 0 696 040. The linear movement of the gear rack is transmitted sinusoidally to the second arcing contact.
In conventional corner gears, the second arcing contact driven in the opposite direction is coupled with the complete travel of the first driven arcing contact either permanently or only temporarily using a low-precision ratchet gear.